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All topics›JavaScript›Linked lists

Linked List Cycle

beginnerlayer B9 · Linked lists5 tests

Return true if the linked list starting at head loops back on itself, and false if walking it eventually reaches null.

  • A cycle exists when some node's next points at a node already visited
  • Do not modify the list
  • Aim for O(1) extra space — a plain Set of nodes works but costs O(n) memory

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